The Sleep Cycle: What you do while you’re asleep

When you’re asleep, your body performs some crucial functions. We believe that the five stages of sleep are essential in contributing to a happy and healthy life. So, what are these five stages of sleep and what happens during them?


Stage 1 Sleep

As your body becomes accustomed to sleep, you begin to feel lighter and more relaxed. Stage 1 sleep lasts for around 10 minutes at most. It’s perfectly normal to find yourself drifting in and out of consciousness in this first cycle of light sleep – you might even still be partially awake.

Ever suddenly felt like you’re falling and then jolt awake? That’s called Hypnic Myoclonia, when your muscles spasm just before your body is about to drift completely out of consciousness. Nobody’s quite sure why it happens – one theory is that it might be primal instinct – but if it is regular and distressing, it’s worth visiting your doctor.

Stage 2 Sleep

You spend about half the night in this state – which is still light sleep – and this is the stage when your body prepares for deep sleep, in which your eyes stop moving, your body cools and your heart rate slows. Random brain spikes happen during this stage, and that’s likely to be because your brain uses this phase of sleep to store long term memories.

Stage 3 & 4 Sleep

Your muscles will go limp and you’ll enter the deepest phase of sleep, where your body will repair tissues and muscles, build energy for the next day, and release appetite-controlling hormones to stop you from overeating the next day. Even loud noises and distractions will struggle to awaken your body at this stage. It’s the worst time to wake up – if you do, expect to feel groggy and confused (this is known as sleep inertia). That’s why you should use a sleep calculator to make sure your morning alarm doesn’t wake you up at this point!

Stage 5 Sleep

This is the REM phase of sleep. Now that your body is rejuvenated and ready for the next day, your brain will begin to store the memories from the day before, and prepare for the day ahead. It’s believed most of the dreaming happens here, because your brain’s activity is increasing. You will also remain paralysed to protect you from accidentally harming yourself at this stage. Towards the end of Stage 5 REM sleep, your heartrate will increase, and your body will naturally begin to awaken. This explains why you often wake from dreams – because dreaming and waking both occur in the same stage of the sleep cycle!

Understanding your sleeping cycles

Whilst our sleep patterns tend to move sequentially, lengths and intensities do vary between each of us. It’s quite normal for light sleep stages to take more time than deep sleep, and our bodies will naturally work out how much of each stage we need. That’s why it’s so important to allow your body to go through the stages without interruption. As your age develops, or if you have certain medical conditions, you will experience less deep sleep.

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